The two Spad Ames followers who had been unconscious had now revived. They occupied two other chairs, and were tied hand and foot. They ogled the grenade and looked as if they wanted to faint.

The pig, Habeas Corpus, was investigating the ankles of the two prisoners. Habeas had abnormally long legs, a lean body, a long snout built for inquiring into things, and two ears so enormous that they might have been mistaken for misplaced wings.

Chemistry, Ham's pet, sat nearby.

"Where is Doc Savage?" asked Mark Colorado.

Monk frowned. "You had better find out who your friends are around here," the homely chemist advised.

"We rescued your sister."

"I watched you do that," Mark Colorado said.

"You-" Monk frowned. "Why didn't you pitch in and help?"

"And let you make me a prisoner, too?"

"n.o.body," disclaimed Monk, "is a prisoner around here."

Mark Colorado glanced at his sister and asked: "What about that?"

"They were asking me questions," the girl said. "And they were beginning to talk about using truth serum."

"That," said Mark Colorado grimly, "is what I was afraid of."

MARK COLORADO moved a little and stood under a light, so that Doc Savage, watching from the darkened vestibule, was able to inspect the thing thoroughly enough to be positive that it was genuine.

Both Monk and Ham were perspiring from the strain.

"One of you call Doc Savage in here," ordered Mark Colorado.

"He isn't here," Ham said."I know better. I saw you go off and leave him, and I hung around in a cab until he left Phenix Academy.

I followed him. While waiting, I asked someone who he was. They told me he was Doc Savage, of whom I have heard and read. It is unfortunate that it had to be Doc Savage."

"Unfortunate?" Ham squinted at him. "What kind of talk is that?"

"You have learned something-"

"Brother, are you mistaken!" Ham interrupted. "We haven't learned anything!"

Mark Colorado said: "You know that Spad Ames is getting a gang together to go back after something he found somewhere in Africa-"

"Africa!" Ham barked. "Who said anything about Africa? It was in the Grand Canyon badlands somewhere."

Mark Colorado showed his teeth grimly. "You see? You do know a great deal."

Monk told Ham disgustedly: "What you better do is shut up before you talk him into letting go of that grenade."

"The fellow is crazy," Ham said. "Anyone who does what he's doing with a grenade is crazy."

"Well, shut up and stop irritating him," Monk yelled, "before he drops that egg!"

Mark Colorado spoke to his sister. He used a dialect which, while not unmusical, was completely unintelligible to Monk and Ham.

Out in the darkened vestibule, perplexed wrinkles appeared on Doc Savage's forehead. The lingo was completely unknown to him, although he could make himself understood in almost any language or dialect, and could speak many of them with native fluency.

Ruth Colorado arose from her chair and picked up the cords with which she had been tied. She went to Monk and Ham in turn and searched them. Then she threw loops over their wrists and began tying them.

"What you think you're doin' with us?" Monk asked uneasily.

"Unfortunately," Mark Colorado said, "you have got to disappear, and not be seen again."

Monk said: "You mean-you're gonna try to kill us?"

"No. You will be taken to the spot which Spad Ames happened to find. You will remain there the rest of your lives."

DOC SAVAGE eased back from the open door, wheeled and entered the section of the penthouse containing Monk's chemical laboratory. Monk and Ham were having their troubles with the Colorados in the residential portion. The laboratory was a series of large rooms done in white, with the apparatus arrayed in spectacular fashion, for while Monk was unquestionably a great industrial chemist, he also loved a show, and one of his proud boasts was that a motion picture producer had recently taken still photographs of the lab to use as a model in constructing a set for some pseudo-scientific picture that was in production.

Chemicals were contained in an array of long metal cabinets in the storeroom. Doc Savage went to the cabinet, and covering his flashlight lens with his palm, except for a small crack of light, he searched. He had worked with Monk here, so he knew the particular container which he wanted.The bottle which he selected, gallon-sized, held a liquid concoction of chemicals which Doc had recently perfected, but which as yet he had not given a practical test.

Ruth Colorado had finished tying Monk and Ham when Doc returned to the vestibule door with the container of chemical.

Mark Colorado, taking a small pillbox from one of his pockets with his hand which did not hold the grenade, said: "You are going to eat some of these. They are sleeping pills, so don't get worried. Ruth, take the pills and make each one swallow about four."

Doc Savage came into the room then. He uncorked the bottle. He dashed the contents over the back of Mark Colorado's head. When Mark Colorado whirled, Doc sloshed more of the chemical liquid into his face.

Ruth Colorado started to leap forward. Doc thrust the gallon bottle at her, and the chemical splashed over her face. She gasped loudly, and clamped her hands to her eyes.

Mark Colorado dropped the grenade. The lever clicked, and inside the thing the timing mechanism began to race off the four or five seconds before it would explode. Doc hurled the bottle of chemical against Mark Colorado; the bottle broke and saturated the man.

With a continuation of the hurling gesture, the bronze man lunged forward and down and got the grenade while it was still rolling.

He threw it through the window, hurled it very hard, so that it would continue outward and upward.

His rush had carried him almost to the window, so he went flat on the floor below the sill, where the masonry would furnish a parapet. Monk and Ham, flopping like fish out of water, had already progressed through a door into a darkened room; they continued their flip-flop progress, their idea to get as far away as fast as possible.

There was white flash, crash; the entire window jumped inward over Doc's head. Gla.s.s landed on his body, jangled on the floor beside him. Grenade fragments, as dangerous as bullets, chopped at the walls.

Habeas Corpus, the pig, and Chemistry, the chimp, dashed for cover.

Mark and Ruth Colorado had raced out into the vestibule, the chemical obviously not having blinded them. Clanging of the elevator door indicated they had entered the lift.

Doc Savage made no effort to stop them.

Chapter VIII. RADIO CLUE.

WHEN Monk and Ham were untied, they had trouble making their voices function. "Blast me, I didn't think I could get so scared!" Monk managed finally.

"You red-headed ape," Ham said unkindly, "if you hadn't been busy big-eyeing that girl, Mark Colorado couldn't have walked in on us like he did."

"Well, there's no danger of you having red hair."

"Why not?"

"n.o.body ever heard of ivory rusting."

Monk and Ham scowled at each other. After a narrow escape, it seemed that they could quiet theirnerves by insulting each other.

When they had gotten rid of some of the scare, Ham said: "Both of those Colorados are nuts, or something. He wasn't fooling with that grenade, and the girl seemed just as calm as he was about it."

"It wasn't quite human, the way they acted," Monk admitted.

"I'll say it wasn't human," Ham agreed. Then Ham realized he was forgetting himself and agreeing with Monk, so he scowled, and snapped, "The girl is all right. She's just got a lot of nerve."

"She had a lot more than nerve," Monk said, and made a shape with his hands. "Boy, what a form!"

"Monk's heart," Ham explained, "sounded like a string of firecrackers."

Monk grinned. "I didn't hear yours making any sound, particularly after her big brother walked in with that iron apple."

Doc Savage had gone outside to the balcony, and by leaning over the cold stone parapet, he could look downward into the lifeless fog that packed the canyon of street that was sixty-odd floors deep. He thought he saw a pale spot that might have been a taxicab headlight move away. He was not sure. The bronze man went back to Monk and Ham.

"Did you learn anything from the girl before her brother arrived?" he asked.

Ham said: "She thanked us for rescuing her. We told her who we were, and she said she was very, very sorry that we had gotten mixed up in this, because it meant that we would have to be taken into the mists."

"Into the mists?" The bronze man's flake-gold eyes seemed to become more animated.

"Into the mists-it sounds silly," Monk interposed. "But that's what she said."

"Was that all?"

"Yes. Of course, we gathered that we were to be taken into the mists, as she put it, because we had found out just a little bit about some tremendous secret. That was the general idea."

"She give information on the black arrowheads?"

"Heck, no! She just told us it was too bad we knew anything at all about black arrowheads."

Monk got up and stamped about the room. "The Colorados got away. Spad Ames got away. So did Locatella. Unless we can get something out of the two prisoners we've got left, we're sunk."

"Which means we may have trouble finding Renny," Ham added.

Doc Savage went into the adjacent room and studied the two hired men of Spad Ames whom they had captured. Some gla.s.s had been sprayed over the pair by the grenade explosion outside, and one of them was staring in fascinated horror at a gouge which a grenade fragment had made in the floor near his head.

"Have you any truth serum?" Doc asked.

"Heck, no!" Monk said. "We told the girl we had some, trying to scare her. But we're out of it."

"Long Tom has a new lie detector," Doc said. "Get hold of him."LONG TOM was Major Thomas J. Roberts, another of Doc Savage's coterie of five a.s.sociates. The fifth member, the long-bodied and long-worded William Harper Johnny Littlejohn, was at present in Mongolia following his occupation of archaeology; he was trying to prove or disprove somebody's claim that the human race had first appeared in that part of the world.

In the interval before Long Tom arrived, the police came, but departed when Doc Savage explained that he would rather handle this matter himself, and when Monk promised to pay for all the grenade damage in the vicinity. After the officers left, it occurred to Monk that he had better ascertain just how much damage he had rashly promised to pay for, and he went out to look.

Doc telephoned the central city police station, and the headquarters of the state police but no trace had been found of his taxicab or of Spad Ames and Locatella.

Monk came back in, muttering. "I must be losing my mind, promising to pay for that damage! I'm financially ruined! Ham, you'll have to loan me some dough."

"You broke again?" Ham demanded.

"Listen, when I was a baby they paid a nurse to push me around in a buggy, and I been pushed for money ever since."

Long Tom Roberts walked in. He was a rather wan-looking fellow with the kind of a complexion that made it seem he must have grown up in a mushroom cave. Long Tom's general physical appearance frequently convinced strangers that he had either just left, or was headed for, a hospital bed. As a matter of fact, no one remembered Long Tom ever having been ill, and he frequently whipped much healthier-looking men than himself, two and three at a time.

"I brought it," he announced triumphantly.

He meant his lie detector. Long Tom was the electrical wizard of their group, and his latest brain child was his lie detector, a supersensitive device which measured tiny electrical currents set up in the body as a part of nerve reaction when an individual told a lie. The device was about the size of a portable radio, and somewhat resembled one, except that there was a large dial and a needle, and electrodes which connected to the victim's wrists.

Monk sniffed and said: "Probably that thing won't work."

"You can ride Ham all you want to," Long Tom told him levelly. "But you mess with me and you'll end up like a postage stamp."

"How do you mean-postage stamp?"

"Licked."

Monk fell silent. The truth was that he was afraid of the aaemic-looking Long Tom, who occasionally flew off the handle without warning and performed somewhat after the fashion of a wild cat.

They questioned the two prisoners, Doc Savage putting the queries.

"What do you know about the black arrowheads?"

"Nothing," both answered.

"What does the talk about going into the mists, and coming out of the mists, mean?""We have no idea."

"Where can we find Spad Ames and Locatella?"

"Don't know."

"To what race of people do the Colorados belong?"

"Can't imagine."